CVE-2026-9086
Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri validation bypass
Summary
### Description A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with `manage-client` permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive `javascript:` or `data:` scheme. This Cross-Site Scripting (XSS) vulnerability allows for arbitrary code execution in the Keycloak origin when a victim clicks the crafted link, such as in the logout flow or the Admin Console.
Affected packages
| Ecosystem | Package | Affected versions | Fixed versions |
|---|---|---|---|
| Maven | org.keycloak:keycloak-services | — | 26.6.4 |
Remediation: Upgrade to 26.6.4 or later.
References
Includes data from the GitHub Advisory Database, licensed under CC-BY 4.0.
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EPSS scores provided by the FIRST.org Exploit Prediction Scoring System.